Public Displays of Affection (PDA)?

As long as you are sure that there are no other unresolved issues with your relationship, I would tell him what you need. You both should be able to compromise and find a middle ground with this issue. Perhaps there is something else bothering him, and he uses the PDA's of a way of telling you so. If you are getting married you need to talk to him, and explain how you feel and that the lack of public affection makes you feel rejected. he should be able to listen.